JPWO2021064776A1 - Fatigue management system - Google Patents

Abstract

The present disclosure provides a fatigue management system capable of managing fatigue of each part of a construction machine more accurately than before. Each of the stress calculation unit S1 that calculates the stress acting on a plurality of parts of the construction machine based on the output of the sensor 18 attached to a part of the construction machine and the construction machine based on the stress calculated by the stress calculation unit S1. It is provided with a damage degree calculation unit S2 for calculating the cumulative damage degree of each part of the construction machine and an index value calculation unit S3 for calculating a fatigue index value weighted by the cumulative damage degree for each part of the construction machine. Fatigue management system S as a feature.

Description

The present disclosure relates to a fatigue management system for construction machinery.

Conventionally, an invention relating to an excavator support device that supports detection of a mismatch between a work content and a work environment and a combination of an operating excavator has been known (see Patent Document 1 below). An object of the present invention is to provide an excavator support device capable of accurately determining whether or not an operating excavator is suitable for the current work content and work environment.

According to one aspect of the above-mentioned conventional invention, an excavator support device including a display screen for displaying an image and a processing device for displaying an image on the display screen is provided (the same document, claim 1, paragraph 0005, etc.). See). The processing apparatus acquires the time history of the evaluation value of the cumulative damage degree accumulated in the excavator parts to be evaluated. Further, the processing apparatus compares the evaluation value of the cumulative damage degree with a determination threshold value that increases with the operating time for determining whether or not the excavator to be evaluated is in a mismatch state. Then, when the evaluation value exceeds the determination threshold value, the processing device notifies that the shovel to be evaluated is in a mismatch state.

In the calculation of the cumulative damage degree, the operation information up to the present time or the cumulative damage degree stored in the storage device is used. The cumulative damage degree can be obtained, for example, by analyzing the stress waveform applied to each evaluation point of the component based on the cumulative fatigue damage rule (see the same document, paragraph 0024, etc.). Specifically, the cumulative damage degree is determined, for example, as follows (see the same document, paragraphs 0064-0076, etc.).

First, the measured values for at least one cycle of a series of operations repeated during work by the excavator are acquired from the posture sensor of the attachment, the load sensor of the attachment, and the turning angle sensor. Next, a plurality of times to be analyzed (hereinafter referred to as "analysis time") are extracted within one cycle of a series of operations. Next, at each of the analysis times, the distribution of stress applied to each of the parts such as the boom and the arm is calculated using the analysis model.

Next, for each evaluation point of each component, the single-cycle damage degree, which is the damage degree accumulated during one cycle operation period, is calculated. Next, by calculating the cumulative damage degree, which is the sum of the single-cycle damage degrees from the start of operation of the machine to the present time, for each excavator to be managed and for each part, the distribution of the cumulative damage degree of the parts can be obtained. calculate. Next, the obtained cumulative damage degree is associated with information such as the machine number and stored in the storage device. In this way, the cumulative damage degree is obtained for each excavator body and each evaluation point of the part.

Japanese Unexamined Patent Publication No. 2016-003462

The cumulative damage degree used in the conventional excavator support device is based on the linear cumulative damage rule which is an empirical rule, and it is assumed that the object leads to fatigue fracture when it reaches 1. However, the cumulative damage degree is essentially a value that includes variation, and in reality, the object leads to fatigue fracture before the cumulative damage degree reaches 1, or even if the cumulative damage degree exceeds 1, the object undergoes fatigue fracture. It does not reach. Therefore, if the cumulative damage degree is used as it is as in the conventional excavator support device, it is not possible to appropriately set the inspection timing for each excavator part.

The present disclosure provides a fatigue management system capable of managing fatigue of each part of a construction machine more accurately than before.

One aspect of the present disclosure is a stress calculation unit that calculates stress acting on a plurality of parts of the construction machine based on the output of a sensor attached to a part of the construction machine, and each said part based on the stress. Fatigue management comprising: a damage degree calculation unit for calculating the cumulative damage degree of the above, and an index value calculation unit for calculating a fatigue index value weighted to the cumulative damage degree for each of the said parts. It is a system.

According to the present disclosure, by using the fatigue index value, it is possible to provide a fatigue management system capable of managing fatigue for each part of a construction machine more accurately than before.

The block diagram which shows the application example of the fatigue management system which concerns on this disclosure. The block diagram which shows one Embodiment of the fatigue management system which concerns on this disclosure. The side view of the hydraulic excavator which is an example of the management target of the fatigue management system of FIG. The block diagram which shows the structure of the hydraulic drive device of the hydraulic excavator of FIG. An example of the relationship between the cumulative damage level of each part of the work machine and the fatigue index value. An example of the relationship between the cumulative damage level of each part of the work machine and the fatigue index value. An example of the relationship between the cumulative damage level of each part of the work machine and the fatigue index value. An example of the relationship between the cumulative damage level of each part of the work machine and the fatigue index value. The flow chart which shows an example of the fatigue index value calculation of the fatigue management system of FIG. FIG. 6 is a flow chart showing an example of processing for calculating the fatigue index value of FIG. 6A. FIG. 6 is a flow chart showing an example of processing for calculating the fatigue index value of FIG. 6A. The image diagram which shows an example of the monitor image of the fatigue management system shown in FIG. The image diagram which shows an example of the monitor image of the fatigue management system shown in FIG. The image diagram which shows an example of the monitor image of the fatigue management system shown in FIG. A graph showing an example of time-series data of fatigue index values of construction machinery. A graph showing an example of time-series data of fatigue index values of multiple construction machines. A side view of a dump truck which is an example of the management target of the fatigue management system of the present disclosure. An image diagram showing an example of a monitor image of a fatigue management system.

Hereinafter, an embodiment of the fatigue management system according to the present disclosure will be described with reference to the drawings.

FIG. 1 is a block diagram showing an application example of the fatigue management system according to the present disclosure. FIG. 2 is a block diagram showing an embodiment of the fatigue management system according to the present disclosure. FIG. 3 is a side view of a hydraulic excavator 10 which is an example of a construction machine. FIG. 4 is a block diagram showing an example of the configuration of the hydraulic drive device 17 of the hydraulic excavator 10 shown in FIG.

The details will be described later, but the fatigue management system S according to the present embodiment has the following main features. The fatigue management system S includes a stress calculation unit S1 that calculates stress acting on a plurality of parts of the construction machine based on the output of a sensor 18 (see FIG. 2) attached to a part of the construction machine. .. Further, the fatigue management system S includes a damage degree calculation unit S2 that calculates the cumulative damage degree of each part of the construction machine based on the stress calculated by the stress calculation unit S1. Further, the fatigue management system S includes an index value calculation unit S3 that calculates a fatigue index value weighted by the cumulative damage degree calculated by the damage degree calculation unit S2 for each part of the construction machine.

The construction machine to be managed by the fatigue management system S is not particularly limited, but is, for example, a hydraulic excavator 10. The hydraulic excavator 10 is, for example, an ultra-large hydraulic excavator used in a mine. Hereinafter, an example of the configuration of the hydraulic excavator 10 to be managed by the fatigue management system S of the present embodiment will be described first, and then the configuration of each part of the fatigue management system S of the present embodiment will be described in detail.

(Hydraulic excavator)
As shown in FIG. 3, the hydraulic excavator 10 includes, for example, a lower traveling body 11, an upper swivel body 12, a cab 13, a front working machine 14, and a controller 15. Further, the hydraulic excavator 10 includes a sensor 18, a transmitter 19A, and a monitor 19B shown in FIG. 2, and an operation lever device 13a and a hydraulic drive device 17 shown in FIG. In the following description, refer to a three-dimensional Cartesian coordinate system consisting of an X-axis parallel to the front-rear direction of the hydraulic excavator 10, a Y-axis parallel to the width direction of the hydraulic excavator 10, and a Z-axis parallel to the height direction of the hydraulic excavator 10. However, each part of the hydraulic excavator 10 may be described.

The lower traveling body 11 has, for example, a pair of crawler-type traveling devices 11a in the width direction (Y direction) of the hydraulic excavator 10. The lower traveling body 11 is driven by, for example, a hydraulic drive device 17, and causes the hydraulic excavator 10 to travel.

The upper swivel body 12 is mounted on the lower traveling body 11 so as to be swivelable. The upper swivel body 12 is driven by, for example, a hydraulic motor or an electric motor (not shown), and swivels with respect to the lower traveling body 11 about a rotation axis parallel to the height direction (Z direction) of the hydraulic excavator 10. .. The upper swing body 12 accommodates various devices such as a prime mover (not shown), a hydraulic pump described later, and a plurality of valves.

The cab 13 is, for example, the passenger compartment of the hydraulic excavator 10 in which the driver's seat on which the operator who operates the hydraulic excavator 10 is boarded is accommodated. The cab 13 is provided, for example, on the upper part of the front portion of the upper swivel body 12 adjacent to the front working machine 14.

The front working machine 14 is provided on the front side of the upper swivel body 12, for example, and is driven by the hydraulic drive device 17 to perform work such as excavation work. The front working machine 14 has, for example, a boom 14a, an arm 14b, and a bucket 14c.

The base end portion of the boom 14a is connected to the upper swing body 12 via, for example, a rotation axis parallel to the width direction (Y direction) of the hydraulic excavator 10. The boom 14a is driven by, for example, an actuator and rotates in a predetermined angle range around a rotation axis attached to the upper swing body 12. As the actuator for driving the boom 14a, for example, a hydraulic cylinder 1 is used. The hydraulic cylinder 1 is a hydraulic actuator driven by the supply of hydraulic oil.

The hydraulic cylinder 1 has, for example, a cylinder tube 1a, a piston 1b, and a rod 1c. The hydraulic cylinder 1 is, for example, a single-rod type hydraulic cylinder in which the rod 1c projects to one side of the cylinder tube 1a. The hydraulic cylinder 1 that drives the boom 14a may be referred to as, for example, the boom cylinder 1A.

In the boom cylinder 1A, one end of the cylinder tube 1a is connected to, for example, an intermediate portion of the boom 14a via a rotation shaft parallel to the width direction (Y direction) of the hydraulic excavator 10. Further, the piston 1b is housed in the cylinder tube 1a and slides in the axial direction of the rod 1c along the inner peripheral surface of the cylinder tube 1a. One end of the rod 1c is connected to the piston 1b inside the cylinder tube 1a. In the boom cylinder 1A, the other end of the rod 1c extends from the inside of the cylinder tube 1a to the outside and is connected to the upper swivel body 12 via, for example, a rotation axis parallel to the width direction (Y direction) of the hydraulic excavator 10. ing.

The base end portion of the arm 14b is connected to the tip end portion of the boom 14a, for example, via a rotation axis parallel to the width direction (Y direction) of the hydraulic excavator 10. The arm 14b is driven by, for example, an actuator and rotates in a predetermined angle range around a rotation axis attached to the boom 14a. As the actuator for driving the arm 14b, for example, a hydraulic cylinder 1 similar to the boom cylinder 1A is used. The hydraulic cylinder 1 that drives the arm 14b may be referred to as, for example, the arm cylinder 1B.

In the arm cylinder 1B, one end of the cylinder tube 1a is connected to, for example, an intermediate portion of the boom 14a via a rotation shaft parallel to the width direction (Y direction) of the hydraulic excavator 10. In the arm cylinder 1B, the other end of the rod 1c opposite to one end of the rod 1c connected to the piston 1b is the base end of the arm 14b via a rotation axis parallel to the width direction (Y direction) of the hydraulic excavator 10. It is connected to the part. The rod 1c of the arm cylinder 1B is connected to, for example, the base end side of the arm 14b with respect to the tip end of the boom 14a.

The base end portion of the bucket 14c is connected to the tip end portion of the arm 14b via a rotation axis parallel to the width direction (Y direction) of the hydraulic excavator 10, for example. The bucket 14c is driven by, for example, an actuator and rotates in a predetermined angle range around a rotation axis attached to the arm 14b. As the actuator for driving the bucket 14c, for example, a hydraulic cylinder 1 similar to the boom cylinder 1A is used. The hydraulic cylinder 1 that drives the bucket 14c may be referred to as, for example, the bucket cylinder 1C.

In the bucket cylinder 1C, one end of the cylinder tube 1a is connected to, for example, the base end of the arm 14b via a rotation axis parallel to the width direction (Y direction) of the hydraulic excavator 10. In the bucket cylinder 1C, the other end of the rod 1c opposite to one end of the rod 1c connected to the piston 1b is connected to the base end portion of the bucket 14c via a link, for example. The link is connected to the rod 1c, for example, via a rotation axis parallel to the width direction (Y direction) of the hydraulic excavator 10.

The controller 15 is hydraulically driven, for example, based on the pilot pressure based on the operation of the operation lever device 13a provided in the cab 13 and the signal from the sensor 18 mounted on the hydraulic excavator 10, which is housed in the upper swing body 12. It controls the device 17. The controller 15 is, for example, a computer unit including a calculation unit 15a such as a central processing unit, a storage unit 15b such as a RAM or ROM, a program stored in the storage unit 15b, and an input / output unit for inputting / outputting signals. be.

The calculation unit 15a, the storage unit 15b, the program, and the input / output unit of the controller 15 constitute a stress calculation unit S1, a damage degree calculation unit S2, and an index value calculation unit S3 of the fatigue management system S. Details of the stress calculation unit S1, the damage degree calculation unit S2, and the index value calculation unit S3 will be described later. In the present embodiment, the stress calculation unit S1, the damage degree calculation unit S2, and the index value calculation unit S3 of the fatigue management system S are provided in, for example, the controller 15 that controls the hydraulic drive device 17, but are separate from the controller 15. It can also be provided. The controller 15 is connected to the sensor 18, the transmitter 19A, and the monitor 19B via a network such as a control area network (CAN).

The hydraulic drive device 17 includes, for example, a hydraulic cylinder 1, a hydraulic pump 2, a pilot pump 3, a bottom pressure sensor 4a, an operating pressure sensor 4b, a hydraulic oil tank 5, and an engine 6. Further, the hydraulic drive device 17 includes, for example, a directional control valve V1, a variable throttle V2, and a variable throttle control valve V3. The hydraulic excavator 10 includes, for example, three hydraulic cylinders 1 of a boom cylinder 1A, an arm cylinder 1B, and a bucket cylinder 1C. However, the configuration of each hydraulic cylinder 1 is the same. Therefore, in FIG. 2, one hydraulic cylinder 1 is shown, and the other two hydraulic cylinders 1 are not shown.

As described above, the hydraulic cylinder 1 includes a cylinder tube 1a, a piston 1b, and a rod 1c. The inside of the cylinder tube 1a is divided by a piston 1b into a bottom side oil chamber 1e located on the proximal end side of the cylinder tube 1a and a rod side oil chamber 1f located on the distal end side of the cylinder tube 1a.

In the hydraulic cylinder 1, when the hydraulic oil is supplied to the bottom side oil chamber 1e, the piston 1b moves to the tip side of the cylinder tube 1a, the hydraulic oil is discharged from the rod side oil chamber 1f, and the rod 1c extends. .. Further, in the hydraulic cylinder 1, when the hydraulic oil is supplied to the rod side oil chamber 1f, the piston 1b moves to the base end side of the cylinder tube 1a, the hydraulic oil is discharged from the bottom side oil chamber 1e, and the rod 1c Shrinks.

More specifically, the boom cylinder 1A rotates the boom 14a around a rotation shaft provided at the base end portion of the boom 14a by extending the rod 1c, and the tip of the boom 14a is set on the hydraulic excavator 10. Move it upward in the height direction (Z direction). Further, the boom cylinder 1A rotates the boom 14a around a rotation shaft provided at the base end portion of the boom 14a by contracting the rod 1c, and the tip of the boom 14a is set in the height direction of the hydraulic excavator 10 ( Move to the lower side in the Z direction).

Further, in the arm cylinder 1B, by extending the rod 1c, the arm 14b is rotated around a rotation axis provided at the base end portion of the arm 14b, and the tip of the arm 14b is pointed in the height direction of the hydraulic excavator 10 ( Move to the lower side in the Z direction). Further, in the arm cylinder 1B, by contracting the rod 1c, the arm 14b is rotated around a rotation axis provided at the base end portion of the arm 14b, and the tip of the arm 14b is pointed in the height direction of the hydraulic excavator 10 ( Move to the upper side in the Z direction).

Further, in the bucket cylinder 1C, by extending the rod 1c, the bucket 14c is rotated around the rotation axis provided at the base end portion of the bucket 14c, and the tip of the bucket 14c is pointed in the height direction of the hydraulic excavator 10 ( Move to the upper side in the Z direction). Further, in the bucket cylinder 1C, by contracting the rod 1c, the arm 14b is rotated around the rotation axis provided at the base end portion of the bucket 14c, and the tip of the bucket 14c is set in the height direction of the hydraulic excavator 10 ( Move to the lower side in the Z direction).

The hydraulic pump 2 is, for example, a swash plate type, radial piston type or sloping shaft type variable displacement hydraulic pump. The hydraulic pump 2 is rotationally driven by the engine 6. The hydraulic pump 2 has, for example, a capacity variable portion 2a made of a swash plate, a swash plate, or the like, and a capacity variable mechanism 2b for driving the capacity variable portion 2a. The capacitance variable mechanism 2b drives the capacitance variable unit 2a based on the command of the controller 15. As a result, the tilt angle of the variable capacity portion 2a changes, and the pump capacity of the hydraulic pump 2 can be increased or decreased. The hydraulic pump 2 discharges pressure oil to the discharge pipeline. The discharge pipe is branched into a center bypass pipe and a branch pipe on the upstream side of the directional control valve V1.

The pilot pump 3 is, for example, a fixed-capacity hydraulic pump. The pilot pump 3 is also rotationally driven by the engine 6. The pilot pump 3 constitutes a pilot hydraulic pressure source together with the hydraulic oil tank 5. The pilot pump 3 discharges pilot pressure oil to the pilot pipeline. The pilot pipeline is on the upstream side of the operation lever device 13a, and the throttle pilot pipeline for supplying pilot pressure oil to the variable throttle control valve V3 side is branched.

The directional control valve V1 switches the pressure oil supplied from the hydraulic pump 2 to the hydraulic cylinder 1 and controls the supply and discharge of the pressure oil to the hydraulic cylinder 1. The directional control valve V1 is composed of a hydraulic pilot type directional control valve at 6 ports and 3 positions. The directional control valve V1 is connected to the hydraulic pump 2 via the discharge pipe, and is connected to the hydraulic oil tank 5 via the center bypass pipe and the return pipe. Further, the directional control valve V1 is connected to the bottom side oil chamber 1e of the hydraulic cylinder 1 via the bottom side pipeline, and is connected to the rod side oil chamber 1f of the hydraulic cylinder 1 via the rod side pipeline.

The variable throttle V2 is provided on the downstream side of the directional control valve V1 in the middle of the center bypass pipeline. The variable throttle V2 variably narrows the flow path area of the center bypass pipeline on the downstream side of the directional control valve V1. The variable throttle V2 is controlled by the pilot pressure oil supplied from the variable throttle control valve V3. In the variable throttle V2, the larger the pilot pressure of the variable throttle control valve V3, the smaller the flow path area, and the smaller the pilot pressure, the larger the flow path area. The pilot pressure of the variable throttle control valve V3 is variably controlled by the controller 15.

The bottom pressure sensor 4a is a pressure sensor that detects the pressure of the pressure oil in the oil chamber 1e on the bottom side of the hydraulic cylinder 1. The bottom pressure sensor 4a detects, for example, the pressure in the bottom side oil chamber 1e or the bottom side pipeline. The bottom pressure sensor 4a is connected to the controller 15 via a signal line, and outputs a detection signal corresponding to the detected pressure of the bottom side oil chamber 1e to the controller 15.

The operating pressure sensor 4b is a pressure sensor that detects the operating amount of the operating lever device 13a. The operating pressure sensor 4b is provided, for example, in the lower pilot line. The operating pressure sensor 4b detects the hydraulic pressure of the lowering side pilot line, that is, the pilot pressure for lowering the boom. The operating pressure sensor 4b is connected to the controller 15 via a signal line, and detects the pilot pressure for boom lowering corresponding to the boom lowering operation amount. The operating pressure sensor 4b outputs a detection signal corresponding to the pilot pressure for lowering the boom to the controller 15.

The sensor 18 is attached to a part of the hydraulic excavator 10, detects a physical quantity, and outputs the physical quantity to the controller 15. More specifically, the sensor 18 includes, for example, a force sensor for detecting a force acting on the hydraulic excavator 10 which is a construction machine, and an attitude sensor for detecting the posture of the hydraulic excavator 10. In the example shown in FIG. 2, the sensor 18 includes a hydraulic sensor 18b as a force sensor, an angle sensor 18a, an angular velocity sensor 18c, an acceleration sensor 18d, an inclination angle sensor 18e, and a stroke sensor (not shown) as attitude sensors. .. The stroke sensor detects the strokes of the boom cylinder 1A, the arm cylinder 1B, and the bucket cylinder 1C, respectively.

The hydraulic sensor 18b is, for example, a pressure sensor that detects the pressure of the hydraulic oil in the oil chamber 1e on the bottom side of the hydraulic cylinder 1. More specifically, the hydraulic pressure sensor 18b is a pressure sensor that detects the pressure of the hydraulic oil in the bottom side oil chamber 1e of the boom cylinder 1A, the arm cylinder 1B, and the bucket cylinder 1C. The hydraulic pressure sensor 18b may be, for example, the above-mentioned bottom pressure sensor 4a. Further, when the lower traveling body 11 and the upper turning body 12 are driven by the hydraulic motor, the hydraulic sensor 18b detects the pressure of the hydraulic oil of the hydraulic motor.

The angle sensor 18a is, for example, a sensor that detects the angle of each part of the construction machine. Specifically, the angle sensor 18a is, for example, a sensor that detects the angle between the upper swing body 12 of the hydraulic excavator 10 and each part of the front working machine 14. More specifically, the angle sensor 18a includes, for example, a rotation axis of the upper swing body 12, a rotation axis of the base end portion of the boom 14a, a rotation axis of the base end portion of the arm 14b, and a base end portion of the bucket 14c. It is provided on each of the rotating shafts of. The angle sensor 18a is, for example, the rotation angle of the upper swivel body 12 with respect to the lower traveling body 11, the rotation angle of the boom 14a with respect to the upper swivel body 12, the rotation angle of the arm 14b with respect to the boom 14a, and the rotation of the bucket 14c with respect to the arm 14b. Detect the angle. The angular velocity sensor 18c is attached to each of the upper swing body 12, the boom 14a, the arm 14b, and the bucket 14c, for example, and detects the angular velocity of each of the upper swing body 12, the boom 14a, the arm 14b, and the bucket 14c. The acceleration sensor 18d is attached to each of the upper swing body 12, the boom 14a, the arm 14b, and the bucket 14c, for example, and detects the acceleration of each of the upper swing body 12, the boom 14a, the arm 14b, and the bucket 14c. The tilt angle sensor 18e is attached to each of the upper swing body 12, the boom 14a, the arm 14b, and the bucket 14c, for example, and detects the tilt angle of each of the upper swing body 12, the boom 14a, the arm 14b, and the bucket 14c. ..

The transmitter 19A is connected to the controller 15, for example, and transmits the fatigue index value output from the controller 15. More specifically, the transmitter 19A transmits the fatigue index value to the server 140 via, for example, the communication satellite 170, the base station 180, and the network 190. Further, the transmitter 19A transmits the fatigue index value to the customer terminal 160A, which is the information terminal 160, by, for example, wireless communication. Further, the transmitter 19A may transmit, for example, the identification information of the hydraulic excavator 10. Further, when the hydraulic excavator 10 is equipped with a positioning device such as a global navigation satellite system (GNSS), the transmitter 19A may transmit the position information of the hydraulic excavator 10.

The monitor 19B is, for example, a display device such as a liquid crystal display device or an organic EL display device arranged in the cab 13. The monitor 19B may include an input device such as a touch panel, for example. The monitor 19B displays, for example, an image in which the fatigue index value output from the controller 15 is associated with a plurality of parts of each component of the hydraulic excavator 10.

With the above configuration, in the hydraulic excavator 10, when the operator operates the operation lever device 13a, the direction control valve V1 is operated by the pressure oil from the pilot pump 3, and the pressure oil of the hydraulic pump 2 is the oil chamber on the bottom side of the hydraulic cylinder 1. It is guided to 1e or the oil chamber 1f on the rod side. As a result, as described above, the hydraulic excavator 10 expands and contracts the rods 1c of the boom cylinder 1A, the arm cylinder 1B, and the bucket cylinder 1C according to the operation amount of the operation lever device 13a, and the boom 14a and the arm 14b. , And each part of the bucket 14c can be operated.

Further, the controller 15 controls the hydraulic motor or the electric motor between the lower traveling body 11 and the upper turning body 12 in response to the operation signal from the operation lever device 13a. As a result, the hydraulic excavator 10 can rotate the upper swivel body 12 with respect to the lower traveling body 11 according to the operation amount of the operation lever device 13a.

(Fatigue management system)
Next, the configuration of each part of the fatigue management system S of the present embodiment will be described in detail. The fatigue management system S of the present embodiment includes, for example, a server 140, a storage device 150, and an information terminal 160, in addition to the stress calculation unit S1, the damage degree calculation unit S2, and the index value calculation unit S3 described above. , Is equipped.

The stress calculation unit S1, the damage degree calculation unit S2, and the index value calculation unit S3 constituting the fatigue management system S of the present embodiment are, for example, by a controller 15 mounted on a construction machine, as shown in FIGS. 2 and 3. Can be configured. The stress calculation unit S1, the damage degree calculation unit S2, and the index value calculation unit S3 constituting the fatigue management system S do not necessarily have to be mounted on the construction machine. For example, the server 140 and the storage device 150 shown in FIG. 1 can be used to configure the stress calculation unit S1, the damage degree calculation unit S2, and the index value calculation unit S3.

As described above, the stress calculation unit S1 calculates the stress acting on a plurality of parts of the construction machine based on the output of the sensor 18 attached to a part of the construction machine. More specifically, the stress calculation unit S1 may use the boom 14a, the arm 14b, and the bucket 14c, respectively, based on, for example, the outputs of the sensors 18 attached to the boom 14a, the arm 14b, and the bucket 14c of the hydraulic excavator 10. Calculate the stress acting on multiple parts of. Although not particularly limited, for example, tens to hundreds of parts can be set for each part.

An example of the stress calculation method by the stress calculation unit S1 is as follows. As shown in FIG. 2, the stress calculation unit S1 uses, for example, a stress calculation formula stored in advance in the storage unit 15b to apply stress acting on each of a plurality of parts of each component constituting the hydraulic excavator 10. calculate. The stress calculation formula is, for example, a formula showing the relationship between the output of the sensor 18 and the stress acting on each of the plurality of parts of the parts constituting the hydraulic excavator 10. The stress calculation formula is obtained in advance for each part of the parts constituting the hydraulic excavator 10 by using, for example, a multiple regression formula or a regression formula using machine learning, and is stored in the storage unit 15b.

An example of the stress calculation formula is shown in the following formulas (1) to (3). In the equations (1) to (3), σ ₁ , σ ₂ , ... Are stresses acting on each of a plurality of parts of the parts constituting the hydraulic excavator 10. Further, in the equations (1) to (3), s ₁ , s ₂ , ... Are the outputs of the sensor 18, M, N and A are constants based on the characteristics of each part, and t is the time. be. In this way, by obtaining the stress calculation formula in advance, the stress acting on each of the many parts of the parts constituting the hydraulic excavator 10 and the time history stress waveform can be simply calculated based on the output of the sensor 18. Can be easily obtained by.

Further, the stress calculation unit S1 calculates, for example, the stress of each part of the hydraulic excavator 10 in the posture reproduced by the acceleration sensor 18d or the gyro sensor and the angle sensor 18a shown in FIG. 2 based on the following equation (4). You may.

In the above equation (4), [M] is a mass matrix, [C] is a damping matrix, [K] is a stiffness matrix, and {u} is a displacement matrix. {F} is an external force acting on the structure, for example, the pressure of the hydraulic cylinder 1, the turning pressure of the upper swing body 12, the hydraulic motor pressure of the lower traveling body 11.

The damage degree calculation unit S2 calculates the cumulative damage degree D of each part based on the stress acting on each part calculated by the stress calculation unit S1. More specifically, the damage degree calculation unit S2 is based on the time history stress waveform acting on each part of each part of the hydraulic excavator 10 and the SN diagram of the stress amplitude and the number of repetitions of each part. The cumulative damage degree D of each part of the above is calculated. The cumulative damage degree D can be calculated by the minor rule shown in the following equation (5) or the modified minor rule after frequency analysis of the time history stress waveform by, for example, the range pair method, the peak valley method, or the rainflow method. can.

The index value calculation unit S3 calculates a fatigue index value weighted by the cumulative damage degree D calculated by the damage degree calculation unit S2 for each part of each part of the hydraulic excavator 10. The fatigue index value is, for example, the usage environment, material properties, and other factors for each excavator 10, each part, and each part, with respect to the cumulative damage degree calculated for each part of each part of the excavator 10. It is an index indicating the degree of fatigue obtained by weighting according to a condition, and is represented by an integer increasing from 1, for example.

5A to 5D show an example of obtaining a fatigue index value from the cumulative damage degree D at each part of each part of the hydraulic excavator 10. In this example, a plurality of maps (A) to (D) are provided so that the weighting conditions are set differently according to the magnitude of the cumulative damage degree D, and one map (A) to (D) is used. A map is selected, and the fatigue index value i is obtained from the selected map based on the cumulative damage degree D. Examples of the map of the fatigue index value i are shown in (A) to (D). In the figure, the range where the cumulative damage degree D is 0.0 to less than 0.35 is the low range, the range where the cumulative damage degree D is less than 0.35 to 0.65 is the medium range, and the range where the cumulative damage degree D is 0.65 or more is the high range. i is an index displayed at a predetermined level, and Lv.1 <Lv.2 <Lv.3 <Lv.4 <Lv. Let it be 5. In the map (A) of FIG. 5A, when the cumulative damage degree D is in the low range, the fatigue index value does not change even if the cumulative damage degree D increases, and a constant Lv. It is set to 1 value, and when it is in the middle range, the fatigue index value is set to Lv. 2. Lv. 3, Lv. It is increased to 4, and when the cumulative damage degree D is in the high range, it does not change even if the cumulative damage degree D increases, and a constant Lv. This is an example of 5. Further, in the map (B) of FIG. 5B, when the cumulative damage degree D is in the low range, the fatigue index value i is set to Lv. 1, Lv2, Lv. Increase to 3 so that the fatigue index value i is constant Lv4 even if the cumulative damage degree D increases when the cumulative damage degree D is in the middle range, and fatigue even if the cumulative damage degree D increases when the cumulative damage degree D is in the high range. The index value does not change, and a constant Lv. This is an example of 5. Further, in the map (C) of FIG. 5C, when the cumulative damage degree D is in the low range and the medium range, the fatigue index value does not change even if the cumulative damage degree D increases, and the constant Lv. In the high range, the fatigue index value i is set to Lv. 2. Lv. 3, Lv. 4, Lv. This is an example of increasing to 5. Further, in the map (D) of FIG. 5D, the fatigue index value i is set to Lv. 1, Lv. 2. Lv. 3, Lv. 4, Lv. Maps (A) and (B) are examples of increasing the fatigue index value relatively early, and maps (C) and (D) are examples of increasing the fatigue index value as the cumulative damage degree D increases. This is an example of increasing the index value. Then, as described above, the storage unit 15b selects a map for each part of the hydraulic excavator 10 which is a work machine from, for example, a plurality of different weighted maps (A) to (D). The conditions for this are stored. The index value calculation unit S3 is among the maps (A), (B), (C) or (D) according to the conditions stored in the storage unit 15b for each part of each component of each hydraulic excavator 10. Select one. Then, the index value calculation unit S3 sets the fatigue index value i from the map selected from the cumulative damage degree D calculated by the damage degree calculation unit S2 to Lv. 1-Lv. 5 is calculated for each part of each part of each hydraulic excavator 10. Hereinafter, some examples of the conditions stored in the storage unit 15b and the selection of the map (A), (B), (C) or (D) based on the conditions will be described.

In the first example of map selection, the condition of the degree of agreement between the stress acting on each part of each part obtained by calculation from the detection result of the sensor 18 and the stress actually acting on each part of each part. Maps (A), (B), (C) or (D) for each part of each part are selected according to the above. The degree of agreement between the stress obtained by the calculation and the actual stress may be empirically obtained from the work history of a work machine such as a hydraulic excavator 10, and the strain is applied to each part of each part of the work machine. It may be based on a comparison between the actual stress experimentally obtained in advance by attaching a stress sensor such as a gauge and the stress obtained by the above calculation. In the latter case, the degree of coincidence between the actual stress and stress due to operation, for example, can be determined based on the coefficient of determination R ^2. Coincidence of the conditions, for example, the coefficient of determination R ² is the highest accuracy in the case of 0.8 or higher the threshold, the coefficient of determination R ² is set a predetermined threshold value of less than 0.8, high accuracy, such as classified into conditions of medium precision, and low precision, it is possible to classify into a number of conditions on the basis of the coefficient of determination R ^2.

The storage unit 15b is, for example, one map (A), (B), (C) or (D) for each part of the work machine from a plurality of maps (A) to (D) having different weightings. As a condition for selecting the above, the condition of the degree of agreement between the actual stress acting on each part of the hydraulic excavator 10 and the stress calculated by the stress calculation unit S1 is stored. More specifically, the storage unit 15b stores, for example, one of four conditions of low accuracy, medium accuracy, high accuracy, and maximum accuracy as the condition of the degree of agreement for each evaluation point. Further, the storage unit 15b has a threshold value of the degree of coincidence, the first maps (C) and (D) that increase the fatigue index value i as the cumulative damage degree D increases, and an increase in the cumulative damage degree D. Along with this, the second maps (A) and (B), which increase the fatigue index value i earlier than the first maps (C) and (D), are stored. When the index value calculation unit S3 calculates the fatigue index value i of each part of each part of the work machine such as the hydraulic excavator 10, the calculated stress and the actual stress of the part stored in the storage unit 15b are calculated. Refer to the condition of the degree of agreement with. Then, the index value calculation unit S3 determines which of the four conditions, low accuracy, medium accuracy, high accuracy, and maximum accuracy, the degree of coincidence of the relevant portion is. The condition of the degree of matching may be, for example, a classification of two conditions of low accuracy and high accuracy, three conditions of low accuracy, medium accuracy, and high accuracy, and may be five or more conditions. ..

Further, the index value calculation unit S3 weights the cumulative damage degree of each part of each part of the work machine according to the determined matching degree condition, for example, one of the maps shown in FIGS. 5A to 5D (A). ), (B), (C) or (D). Specifically, the index value calculation unit S3 selects, for example, the first map (C) or (D) when the degree of matching is equal to or greater than the threshold value for each part of the work machine, and matches. Select the second map (A) or (B) if the degree is below the threshold. More specifically, for example, when the degree of matching is classified into the above four conditions, the index value calculation unit S3 may use FIG. 5B if the condition of the degree of matching of a certain part selected at the time of calculating the fatigue index value is low accuracy. Select the map (B) shown in. As a result, the fatigue index value i of the site starts to increase from the stage where the cumulative damage degree D is relatively low. Further, the index value calculation unit S3 selects, for example, the map (A) shown in FIG. 5A if the condition of the degree of matching of the selected parts is medium accuracy, and the map shown in FIG. 5D if the condition is high accuracy. Select D), and if it is more accurate, that is, the highest accuracy, select the map (C) shown in FIG. 5C. As a result, as the degree of coincidence of the relevant portion increases, the increase in the fatigue index value i with the increase in the cumulative degree of damage becomes gradual.

That is, if the degree of coincidence between the calculated stress and the actual stress of the selected portion is the highest accuracy, the index value calculation unit S3 is damaged due to an increase in the cumulative damage degree D as shown in the map (C) shown in FIG. 5C. After the risk of the above increases, the fatigue index value i is rapidly increased. Further, if the degree of coincidence between the calculated stress and the actual stress of the selected portion is highly accurate, the index value calculation unit S3 will increase the cumulative damage degree D and the fatigue index as shown in the map (D) of FIG. 5D. The value i is gradually increased, and the fatigue index value i is increased earlier than when the degree of coincidence is more accurate. Further, if the degree of coincidence between the calculated stress and the actual stress of the selected portion is medium accuracy, the index value calculation unit S3 will increase the cumulative damage degree D to some extent as shown in the map (A) shown in FIG. 5A. After the risk increases, the fatigue index value i is increased earlier than in the case where the degree of agreement is high accuracy. Further, in the index value calculation unit S3, if the degree of coincidence between the calculated stress and the actual stress of the selected portion is low, as shown in the map (B) shown in FIG. 5B, the degree of coincidence is higher than that of the case of medium accuracy. Also raises the fatigue index value i at an early stage to call attention.

In the second example of map selection, the map (A), (B), (C) or (D) is selected according to the risk of damage. Specifically, the storage unit 15b selects one map (A), (B), (C) or (D) for each part of each part of the work machine from a plurality of different weights, for example. As a condition of, the risk of damage to each part is classified into the highest risk, the high risk, and the other three conditions and stored. When calculating the index value of each part of each part of the work machine such as the hydraulic excavator 10, the index value calculation unit S3 refers to the risk condition of each part stored in the storage unit 15b, and refers to the risk condition of the part. Determine if the risk of breakage is the highest risk, the highest risk, or the other. The conditions for the risk of damage may be, for example, high risk and other two conditions, or four or more conditions.

Further, the index value calculation unit S3 weights the cumulative damage degree D of each part of each part of the work machine according to the determined damage risk condition, for example, any of the maps shown in FIGS. 5A to 5D. Select A), (B), (C) or (D). Specifically, for example, when the damage risk is classified into the above three conditions, the index value calculation unit S3 shows in FIG. 5B if the damage risk of a certain part selected at the time of calculating the fatigue index value i is the highest risk. Select the map (B). As a result, the fatigue index value i of the site starts to increase from the stage where the cumulative damage degree D is relatively low. Further, the index value calculation unit S3 selects the map (A) shown in FIG. 5A if, for example, the risk of damage to the selected portion is high, and the map shown in FIG. 5C or FIG. 5D otherwise. Select C) or (D). As a result, as the risk of damage to the site increases, the fatigue index value i increases earlier as the cumulative damage degree D increases.

In the third example of map selection, a map (A), (B), (C) or (D) is selected according to the degree of influence on the work machine when each part is damaged. Specifically, the storage unit 15b selects one map (A), (B), (C) or (D) for each part of each part of the work machine from a plurality of different weights, for example. The degree of influence on the work machine for each part is classified into three conditions, for example, the degree of influence that the operation of the work machine is stopped, the degree of influence that the operation of the work machine is concerned about, and the other three conditions. It is remembered. The index value calculation unit S3 determines the condition of the degree of influence of each part stored in the storage unit 15b on the work machine when calculating the fatigue index value i of each part of each part of the work machine such as the hydraulic excavator 10. With reference to it, it is determined whether the degree of influence of the site is high, medium, or other. The classification of the degree of influence may be, for example, a classification of a large degree of influence and another two-stage classification, or may be a classification of four or more stages.

Further, the index value calculation unit S3 weights the cumulative damage degree D of each part of each part of the work machine according to the determined influence degree, for example, any of the maps (A) shown in FIGS. 5A to 5D. , (B), (C) or (D). Specifically, for example, when the degree of influence is classified into the above three conditions, the index value calculation unit S3 may use the map shown in FIG. 5B if the degree of influence of a certain part selected during the calculation of the fatigue index value i is large. Select (B). As a result, the fatigue index value of the site starts to increase from the stage where the cumulative damage degree is relatively low. Further, the index value calculation unit S3 selects the map (A) shown in FIG. 5A if the degree of influence of the selected portion is medium, and the map (C) shown in FIG. 5C or FIG. 5D otherwise. Or select (D). As a result, as the degree of influence of damage to the site increases, the fatigue index value i rises at an early stage as the cumulative degree of damage increases.

In the fourth example of map selection, a map (A), (B), (C) or (D) is selected according to the effect on the safety of the work machine when each part is damaged. Specifically, the storage unit 15b selects one map (A), (B), (C) or (D) for each part of each part of the work machine from a plurality of different weights, for example. As a condition of, the influence on the safety of the work machine is classified into two conditions, that is, whether or not the part is a safety-related part or a safety-related part, and is stored. The index value calculation unit S3 refers to the condition regarding the influence on the safety of the work machine stored in the storage unit 15b when calculating the fatigue index value i of each part of each part of the work machine such as the hydraulic excavator 10. , Determine whether the part is a safety-related part or a safety-related part.

Further, the index value calculation unit S3 weights the cumulative damage degree D of each part of each part of the work machine according to the determined condition, for example, any of the maps (A) shown in FIGS. 5A to 5D. Select (B), (C) or (D). Specifically, for example, if the part selected during the calculation of the fatigue index value i is a safety-related part or a safety-related part, the index value calculation unit S3 may use the map (A) shown in FIGS. 5A or 5B. Select B), otherwise select the maps (C) and (D) shown in FIGS. 5C and 5D. As a result, the fatigue index value i of the site increases earlier if the site is a safety-related part or a safety-related site than if the site is not.

In the fifth example of map selection, the map (A), (B), (C) or (D) is selected according to the replacement time and repair time of the part including each part. Specifically, the storage unit 15b selects one map (A), (B), (C) or (D) for each part of each part of the work machine from a plurality of different weights, for example. As a condition of, the difficulty of replacement / repair for each part is, for example, the difficulty of replacing or repairing parts takes a long time and the difficulty of requiring a work vehicle, and the difficulty of replacement or repair takes time, but a work vehicle is required. It is memorized by being classified into three conditions, medium difficulty and other low difficulty. The index value calculation unit S3 refers to the replacement / repair difficulty of each part stored in the storage unit 15b when calculating the fatigue index value i of each part of each part of the work machine such as the hydraulic excavator 10. Determine the difficulty of replacing / repairing parts including the relevant part. In addition, the classification of the replacement / repair difficulty may be, for example, a classification of two stages of difficulty and other two stages, or may be a classification of four or more stages.

Further, the index value calculation unit S3 weights the cumulative damage degree of each part of each part of the work machine according to the determined condition of the replacement / repair difficulty, for example, one of the maps shown in FIGS. 5A to 5D. Select (A), (B), (C) or (D). Specifically, for example, when the replacement / repair difficulty is classified into the above three conditions, if the replacement / repair difficulty of a certain part selected when the fatigue index value is calculated is high, the index value calculation unit S3 is shown in FIG. 5B. Select the map (B) shown in. As a result, the fatigue index value i of the site starts to increase from the stage where the cumulative damage degree is relatively low. Further, the index value calculation unit S3 selects, for example, the map (A) shown in FIG. 5A if the replacement / repair difficulty of the selected part is medium, and the map shown in FIG. 5C or FIG. 5D otherwise. Select C) or (D). As a result, as the difficulty level of replacement / repair of the relevant portion increases, the fatigue index value increases at an early stage as the cumulative damage level D increases.

In addition, as an example of map selection other than the above, for example, depending on each condition such as good or bad access to a work site such as a mine, psychological influence on the user, usage of the car body, influence of excavated material, etc. The map (A), (B), (C) or (D) of FIG. 5D may be selected from 5A.

The server 140 performs data communication with a plurality of construction machines. The server 140 performs data communication with, for example, a plurality of hydraulic excavators 10 via a communication satellite 170, a base station 180, a line network 190, and the like. The line network 190 is, for example, a communication line including an Internet line. Further, the server 140 performs data communication with a plurality of hydraulic excavators 10 via, for example, a customer terminal 160A which is an information terminal 160 and a line network 190.

The storage device 150 is connected to the server 140 via a line, for example. The storage device 150 includes, for example, an index value database 150A and a customer information database 150B. The index value database 150A stores, for example, the fatigue index values of each of a plurality of construction machines. The customer information database 150B stores, for example, various information about a plurality of individual customers. Further, as described above, the storage device 150 is, for example, from the plurality of maps (A) to (D) shown in FIGS. 5A to 5D for each part of each part of the hydraulic excavator 10 which is a work machine. The conditions for selecting one map may be stored.

The information terminal 160 performs data communication with the server 140. The information terminal 160 includes, for example, a customer terminal 160A and an information terminal 160B used by service personnel, customers, sellers, and the like. For example, the customer terminal 160A is arranged at a site where the hydraulic excavator 10 is used, performs data communication with a plurality of hydraulic excavators 10 by wireless communication, and performs data communication with the server 140 via the line network 190 by wireless communication or wired communication. conduct. Further, the information terminal 160B is, for example, a desktop computer, a notebook computer, or a mobile information terminal used by service personnel, customers, and sellers, and performs data communication with the server 140 by wired communication or wireless communication.

The fatigue management system S of the present embodiment includes, for example, an image generation unit that generates an image in which each part of a construction machine is associated with a fatigue index value, and an image display device that displays the image. The image generation unit may be, for example, a part of the index value calculation unit S3. That is, the index value calculation unit S3 also functions as an image generation unit that generates an image in which each part of each part of the hydraulic excavator 10 and the fatigue index value of each part are associated with each other, for example. In this case, the monitor 19B can be used as an image display device. The information terminal 160 may include an image generation unit and an image display device, the server 140 may include an image generation unit, and the information terminal 160 may include an image display device.

Further, as described above, the fatigue management system S of the present embodiment has a server 140 that performs data communication with a plurality of construction machines, a storage device 150 connected to the server 140, and information that performs data communication with the server 140. It is equipped with a terminal 160. In this case, the information terminal 160 may have a comparison unit for comparing the degree of fatigue based on the time series data of the fatigue index value.

Hereinafter, the operation of the fatigue management system S of the present embodiment will be described with reference to FIGS. 6A to 9. FIG. 6A is a flow chart showing an example of a flow of calculating a fatigue index value by the fatigue management system S shown in FIG. 2.

The fatigue management system S, for example, starts calculating the fatigue index value i when the operator starts the hydraulic excavator 10. First, the stress calculation unit S1 performs determination P1 for the presence / absence of uncalculated data among the data acquired from the sensor 18. Specifically, in the determination P1, the stress calculation unit S1 searches for the data acquired from the sensor 18, and if there is new data that has not been processed in the past (YES), the process P2 for reading the data is performed. conduct. On the other hand, in the determination P1, when there is no new data that has not been processed in the past (NO), the stress calculation unit S1 performs the process P3 that waits for a certain period of time, and then returns to the determination P1.

When the data is read in the process P2, the stress calculation unit S1 selects one uncalculated evaluation point from which the stress has not been calculated from the plurality of evaluation points corresponding to the plurality of parts of each component of the hydraulic excavator 10. Process P4 is performed. In the process P4, individual numbers are assigned to all the evaluation points, and the stress calculation unit S1 selects one point at a time from the uncalculated evaluation points having the smallest number in ascending order.

After the processing P4 is completed, the stress calculation unit S1 uses the calculation formulas such as the formulas (1) to (3) and the data acquired from the sensor 18, and the stress waveform in the time series at the selected evaluation point, that is, , Process P5 for calculating the time history stress waveform is performed. After that, the damage degree calculation unit S2 performs the process P6 for calculating the cumulative damage degree at the selected evaluation points based on the time history stress waveform calculated by the stress calculation unit S1 as described above. Further, as described above, the index value calculation unit S3 performs the process P7 to calculate the fatigue index value i of the selected evaluation point using the cumulative damage degree D calculated by the damage degree calculation unit S2.

FIG. 6B is a flow chart showing an example of the process P7 for calculating the fatigue index value shown in FIG. 6A. As shown in FIG. 6B, the index value calculation unit S3 executes the first determination process P71 for the selected evaluation points corresponding to one of the respective parts of each part of the hydraulic excavator 10 which is a work machine. In the first determination process P71, the index value calculation unit S3 has a map (A), one of the different maps (A) to (D) stored in the storage device 150 for the selected evaluation points. Determine the conditions for selecting (B), (C) or (D).

Specifically, for example, as in the first example of map selection described above, the stress acting on each part of the hydraulic excavator 10 which is a working machine obtained by calculation from the detection result of the sensor 18. , It is assumed that the map (A), (B), (C) or (D) is selected for each part according to the condition of the degree of agreement with the stress actually acting on each part of each part. In this case, the index value calculation unit S3 refers to, for example, the condition of the degree of matching of the evaluation points stored in the storage device 150 in advance for the selected evaluation points in the first determination process P71, and matches the evaluation points. Determine if the degree condition is highly accurate.

When the index value calculation unit S3 determines in the first determination process P71 that the condition of the degree of matching of the selected evaluation points is not high accuracy (NO), the second map (A) shown in FIG. 5A or FIG. 5B or The process P72 for selecting (B) is executed. Further, in the first determination process P71, when the index value calculation unit S3 determines that the matching degree of the selected evaluation points is highly accurate (YES), the first map (C) shown in FIG. 5C or FIG. 5D or The process P72 for selecting (D) is executed. After that, in the fatigue index value calculation process P74, the index value calculation unit S3 calculates the fatigue index value of the selected evaluation point from the selected map based on the cumulative damage degree D.

FIG. 6C is a flow chart showing another example of the process P7 for calculating the fatigue index value i shown in FIG. 6A. In the example shown in FIG. 6B, the index value calculation unit S3 has high accuracy according to the condition of the degree of coincidence between the stress calculated by the calculation of each evaluation point and the actual stress by the first determination process P71. And, it was classified into two conditions when it was not so. However, in the example shown in FIG. 6C, the index value calculation unit S3 executes the first determination process P71 and the second determination process P75, and as described above, the stress due to the calculation of each evaluation point and the actual stress. It is also possible to determine the three conditions of the degree of agreement with.

Specifically, in the example shown in FIG. 6C, the index value calculation unit S3 executes the first determination process P71 in the same manner as in the example shown in FIG. 6B, and the condition of the degree of agreement of the selected evaluation points is high accuracy or the highest. If it is determined that the accuracy is not (NO), the process P72 for selecting the second map (A) or (B) shown in FIG. 5A or FIG. 5B is executed. Further, in the first determination process P71, the index value calculation unit S3 further executes the second determination process P75 when it is determined that the condition of the degree of matching of the selected evaluation points is high accuracy or the highest accuracy (YES). In the second determination process P75, the index value calculation unit S3 determines whether or not the condition of the degree of matching of the selected evaluation points is the highest accuracy, and determines that the accuracy is not the highest (NO), as shown in FIG. 5D. The process P76 for selecting the first map (D) is executed, and when it is determined that the accuracy is the highest (YES), the process P77 for selecting the first map (C) shown in FIG. 5C is executed. After that, in the index value calculation process P74, the index value calculation unit S3 calculates the fatigue index value i of the selected evaluation point from the selected map based on the cumulative damage degree D.

Although not shown, in addition to the first determination process P71, the process P72 to the process 74, the second determination process P75 process 76 and the process 77, a new condition determination process and a map are selected based on the determination process. A new selection process may be added. Thereby, as described above, it is also possible to determine four or more conditions of the degree of agreement between the stress calculated by the calculation of each evaluation point and the actual stress. Further, in the process P7 for calculating the index value, the index value calculation unit S3 uses the processing flow as shown in FIGS. 6B and 6C according to conditions other than the degree of coincidence between the stress calculated by each evaluation point and the actual stress. , Map (A), (B), (C) or (D) may be selected.

Specifically, in the first determination process P71 of the flow shown in FIG. 6B, the index value calculation unit S3 is a component of each component of the hydraulic excavator 10, which is a work machine, as in the second example of map selection described above. It may be determined whether or not the risk of damage to the site is high, or whether or not the effect on the safety of each site is large as in the fourth example of map selection described above. Further, the index value calculation unit S3 determines whether or not the degree of influence on the operation of the work machine is large in the first determination process P71 of the flow shown in FIG. 6C, as in the third example of the map selection described above. Then, in the second determination process P75, it may be determined whether or not the influence on the operation of the work machine is small. Further, the index value calculation unit S3 determines whether or not the replacement / repair difficulty is medium or low in the first determination process P71 of the flow shown in FIG. 6C, as in the fifth example of map selection described above. The determination may be made, and it may be determined in the second determination process P75 whether or not the replacement / repair difficulty is low. In these cases as well, the index value calculation unit S3 subsequently executes the process P72, the process P73, the process 76, or the process 77 to select the weighting for each evaluation point, and accumulates from the selected map in the fatigue index value calculation process P74. The fatigue index value of the selected evaluation point is calculated based on the damage degree D.

Next, in the determination P8 shown in FIG. 6A, the fatigue management system S is subjected to, for example, stress and cumulative damage to all evaluation points by the stress calculation unit S1, the damage degree calculation unit S2, or the index value calculation unit S3. Determining whether or not the degree or fatigue index value has been calculated. As a result of the determination P8, when the calculation of all the evaluation points is not completed (NO), the process returns to the process P4. On the other hand, when the calculation of all the evaluation points is completed as a result of the determination P8 (YES), the index value calculation unit S3 has, for example, the threshold of each evaluation point in which the fatigue index value is stored in the storage unit 15b. The determination P9 of whether or not the value is exceeded is performed.

In this determination P9, the index value calculation unit S3 may compare each fatigue index value of all the evaluation points with the threshold value of each evaluation point, or may compare each of the plurality of evaluation points selected in advance. The fatigue index value may be compared to the threshold of each selected evaluation point. As a result of the determination P9, when the fatigue index value exceeds the threshold value at any of the evaluation points, for example, the index value calculation unit S3 transmits an alarm recommending inspection of the portion corresponding to the evaluation point. It can be transmitted to the information terminal 160 via the machine 19A or displayed on the monitor 19B.

After the determination P9 is completed, the index value calculation unit S3 performs, for example, the process P10 for outputting the fatigue index values of all the evaluation points to the monitor 19B and the storage unit 15b, and returns to the determination P1. The determination P1 to the process P10 can be repeated, for example, from the time when the start switch of the hydraulic excavator 10 is turned on to the time when the start switch of the hydraulic excavator 10 is turned off.

As described above, the fatigue management system S of the present embodiment includes a stress calculation unit S1, a damage degree calculation unit S2, and an index value calculation unit S3. The stress calculation unit S1 calculates the stress acting on a plurality of parts of the construction machine based on the output of the sensor 18 attached to a part of the construction machine. The damage degree calculation unit S2 calculates the cumulative damage degree of each part based on the stress calculated by the fatigue management system S. The index value calculation unit S3 calculates a fatigue index value weighted by the cumulative damage degree for each part.

With this configuration, the fatigue management system S is, for example, fatigue of each part of the construction machine according to the conditions specific to each construction machine, each part of the construction machine, and each of the plurality of parts of each part. Can be managed more accurately than before.

More specifically, the cumulative damage degree directly used in the conventional excavator support device is based on the linear cumulative damage rule, which is an empirical rule, and when it reaches 1, the object suffers fatigue fracture. It is assumed that it will reach. However, the cumulative damage degree is essentially a value that includes variation, and in reality, the object leads to fatigue fracture before the cumulative damage degree reaches 1, or even if the cumulative damage degree exceeds 1, the object undergoes fatigue fracture. It does not reach. Therefore, if the cumulative damage degree is used as it is as in the conventional excavator support device, there is a possibility that the measures against fatigue at each excavator site are insufficient, or conversely, excessive measures cause waste.

On the other hand, the fatigue management system S of the present embodiment calculates a fatigue index value weighted by the cumulative damage degree by the index value calculation unit S3 for each part. Thereby, for example, depending on the conditions specific to each of the hydraulic excavator 10, the upper swing body 12, the boom 14a, the arm 14b, the bucket 14c, and the plurality of parts of the hydraulic excavator 10, respectively. It is possible to manage the fatigue of the part.

More specifically, for example, among the parts of the hydraulic excavator 10, the fatigue index value of a part having a high risk of failure or a specific part of the part is higher than the fatigue index value of another part or another part. Therefore, the cumulative damage degree can be weighted. Therefore, by using the fatigue index value calculated by the index value calculation unit S3, it is possible to manage the fatigue of a part having a high risk of fracture and a specific part with higher accuracy and safety.

Further, in the fatigue management system S of the present embodiment, for example, at a site where access is difficult, such as a remote mine, the fatigue index value is larger than that at a site where access is easy, and the cumulative damage is caused by the index value calculation unit S3. It is also possible to set the weighting of degrees. This makes it possible to request inspections of construction machinery at sites that are difficult to access earlier than sites that are easily accessible, enabling highly accurate fatigue management of construction machinery according to the environment of the site. Become.

Further, in the fatigue management system S of the present embodiment, for example, in a construction machine, a fatigue index value is larger than that of other parts or parts in a part that takes time to be replaced or repaired or a part where maintenance is difficult. , It is also possible to set the weighting of the cumulative damage degree by the index value calculation unit S3. This enables highly accurate fatigue management of construction machines according to the characteristics of each part of the construction machine and the ease of maintenance of each part.

Further, in the fatigue management system S of the present embodiment, the sensor 18 includes a force sensor that detects a force acting on the construction machine and an attitude sensor that detects the posture of the construction machine. Such a force sensor or an attitude sensor has been conventionally attached to a construction machine for a purpose different from the purpose of calculating the stress acting on a plurality of parts of the construction machine. Therefore, it is not necessary to attach a sensor such as a strain gauge only for calculating stress to the construction machine.

Further, the fatigue management system S of the present embodiment has one map (A), (B), (C) for each part of the hydraulic excavator 10 from a plurality of different maps (A) to (D). Alternatively, the storage unit 15b or the storage device 150 in which the conditions for selecting (D) are stored is provided. Then, the index value calculation unit S3 displays one map (A), (B), (C) or (D) according to the conditions stored in the storage device 150 for each part of the hydraulic excavator 10. select. With this configuration, the method of increasing the fatigue index value with the increase in the cumulative damage degree can be different depending on the conditions for each part of the hydraulic excavator 10, and the fatigue of each part and each part can be different. It becomes possible to manage more accurately according to the conditions.

Further, in the fatigue management system S of the present embodiment, the storage unit 15b or the storage device 150 has each of the hydraulic excavators 10 as a condition for selecting the map (A), (B), (C) or (D). The degree of coincidence between the actual stress acting on the portion and the stress calculated by the stress calculation unit S1 is stored. Further, the storage unit 15b or the storage device 150 has a threshold value of the degree of coincidence, a first map (C) or (D) that increases the fatigue index value as the cumulative damage degree increases, and a cumulative damage degree. A second map (A) or (B), which increases the fatigue index value earlier than the first map (C) or (D) with the increase of the first map (C) or (D), is stored. Then, the index value calculation unit S3 selects the first map (C) or (D) for each part of the hydraulic excavator 10 when the degree of coincidence is equal to or greater than the threshold value, and the degree of coincidence is equal to or higher than the threshold value. If it is lower than the threshold value, the second map (A) or (B) is selected.

With this configuration, when the degree of coincidence is equal to or higher than the threshold value, that is, the degree of coincidence increases the fatigue index value with respect to the degree of cumulative damage of the portion where the stress calculation by the index value calculation unit S3 is highly accurate. When it is lower than the threshold value, that is, the stress calculation by the index value calculation unit S3 can be made slower than the increase of the fatigue index value with respect to the cumulative damage degree of the portion where the accuracy is not high. In other words, in a region where the stress calculation accuracy by the stress calculation unit S1 is lower than a predetermined threshold value, the fatigue index value increases earlier with respect to the cumulative damage degree than in other regions, so that the fatigue of that region is fatigued. Attention is drawn to. Therefore, it becomes possible to manage the fatigue of each part of the hydraulic excavator 10 more accurately than before, and it is possible to further improve the safety of the fatigue management system S.
Further, in the above, the fatigue index value is obtained based on the maps (A) to (D) selected under the above conditions based on the cumulative damage degree D calculated by the equation (5), but the following equation (6) is used. ) Can also be calculated.

An example of the calculation formula of the fatigue index value is shown in the following formula (6). In the formula (6), i ₁ , i ₂ , ... Are fatigue index values of each part of each part. a is an arbitrary coefficient. w _a1 , w _a2 , ... And w _b1 , w _b2 , ... and b ₁ , b ₂ , ... Are numerical values for weighting specific to each part of each part of the hydraulic excavator 10. d ₁ , d ₂ , ... Are the cumulative damage degrees of each part of each part obtained by the formula (5).

Each hydraulic excavator 10, according to the use environment, material properties, and other conditions for the site of each component and each weighting _{w a1, w a2,} ... and _{w b1, w b2,} ... and _b 1, b _2, ... Is stored in the storage unit 15b together with, for example, an arithmetic expression such as the expression (6). These weightings can be arbitrarily set by, for example, a user or seller of the fatigue management system S inputting information to the input device of the monitor 19B or the input device of the information terminal 160 according to an individual request or environment. It can be changed. The concept of weighting can be set by the same concept as described above. For example, the above-mentioned maps (A) to (D) are weighted maps in which the relationship between the _{cumulative damage degree d and the weighted w a} and w _{b is preset.} It may be created as, and selected under the same conditions as above. Then, the index value calculation unit S3 uses, for example, an calculation formula as shown in the formula (6), and the fatigue index values i ₁ and _{are derived from the cumulative damage degrees d 1} , d _{2, ... Calculated by the damage degree calculation unit S2.} i ₂ , ... is calculated. The fatigue index value i in this case is an index without an upper limit.

Further, the fatigue management system S of the present embodiment includes, for example, an index value calculation unit S3 that functions as an image generation unit that generates an image in which each part of the hydraulic excavator 10 which is a construction machine is associated with the fatigue index value. ing. Further, the fatigue management system S of the present embodiment includes a monitor 19B as an image display device for displaying an image generated by the image generation unit. With this configuration, the fatigue index value can be visually indicated, for example, as shown in FIGS. 7A to 7C.

7A to 7C are image diagrams showing an example of the image G displayed on the monitor 19B shown in FIG. 2 in the fatigue management system S shown in FIG. In the example shown in FIG. 7A, the monitor 19B displays an image G in which each of the plurality of parts of the arm 14b of the hydraulic excavator 10 is associated with the fatigue index value. In the image G, for example, 10 points from an arbitrary point a to a point j are selected from a plurality of parts of the arm 14b. The fatigue index value is, for example, the level Lv. For each of the sites from the point a to the point j of the arm 14b. Level 1 to level Lv. It is displayed as an "index" in 5 stages up to 5. Level Lv. In 1, the fatigue index value is the smallest in 5 stages, and the level Lv. 5 has the largest fatigue index value in 5 stages.

In the example shown in FIG. 7A, the image G is an image of the arm 14b, a leader line drawn from a portion of the arm 14b from a point a to a point j, and a character displayed at the tip of the leader line to indicate each portion. The circle containing is displayed. This circle is displayed, for example, in diameter and color according to the level of the index. Specifically, for example, when the index level is high and the fatigue index value is high, the diameter of the circle corresponding to each part is displayed large, and when the index level is low and the fatigue index value is low, each part is displayed. The diameter of the circle corresponding to is displayed small. Also, for example, if the index level is high and the fatigue index value is high, the circles and table cells corresponding to each part will be darkened, and if the index level is low and the fatigue index value is low, each part will be darkened. The corresponding circles and table cells are dimmed. Thereby, the fatigue index value of each part of each part of the hydraulic excavator 10 can be visually shown.

In the example shown in FIG. 7B, the monitor 19B displays an image G in which each of the plurality of parts of the structure constituting the upper swing body 12 of the hydraulic excavator 10 is associated with the fatigue index value. Further, in the example shown in FIG. 7C, the monitor 19B displays an image G in which each of the plurality of parts of the structure constituting the lower traveling body 11 of the hydraulic excavator 10 is associated with the fatigue index value. Also in these examples, the fatigue index value of each part of each part of the hydraulic excavator 10 can be visually shown as in the example shown in FIG. 7A. In these examples, 10 predetermined locations are displayed in the structures of the arm 14b, the upper swing body 12, and the lower traveling body 11, but any predetermined fatigue index value exceeding a preset predetermined fatigue index value is displayed. The fatigue index value may be displayed in the same manner for the part of.

Further, the fatigue management system S of the present embodiment includes a server 140 that performs data communication with a plurality of construction machines, a storage device 150 connected to the server 140, and an information terminal 160 that performs data communication with the server 140. I have. The information terminal 160 has, for example, a comparison unit that compares the degree of fatigue based on the time-series data of the fatigue index value. With this configuration, for example, the degree of fatigue of a specific part of a construction machine can be compared with the threshold value thereof, and the degree of fatigue of a specific part of the construction machine can be managed more accurately. In addition, the degree of fatigue can be compared among a plurality of construction machines.

FIG. 8 is a graph showing an example of time-series data of the fatigue index value of a specific construction machine. More specifically, FIG. 8 is time-series data of the fatigue index value at point e shown in FIG. 7A of the boom 14a of Unit A, which is one of a plurality of hydraulic excavators 10, for example. In this way, the transition of the fatigue level at point e can be grasped from the time-series data of the fatigue index value, and when the fatigue level at point e reaches a predetermined threshold value, for example, an alarm recommending inspection is issued. It will be possible to take appropriate measures such as issuing.

FIG. 9 is a graph showing an example of time-series data of fatigue index values of a plurality of construction machines. More specifically, FIG. 9 shows, for example, the fatigue index value at point e shown in FIG. 7A in each boom 14a of the four hydraulic excavators 10 from the A to the D units among the plurality of hydraulic excavators 10. It is time series data. In the example shown in FIG. 9, the comparison unit of the information terminal 160 compares the degree of fatigue of each hydraulic excavator 10 based on the time series data of the fatigue index values of the four hydraulic excavators 10 from the A unit to the D unit. .. From this, it can be seen that the fatigue level of Unit B is the highest and the fatigue level of Unit C is the lowest. Thereby, for example, the hydraulic excavator 10 having a high degree of fatigue is arranged in the work having a low load, and the hydraulic excavator 10 having a low degree of fatigue is arranged in the work having a high load. It becomes possible to make a work plan. The fatigue index value used in FIGS. 8 and 9 is a fatigue index value obtained as an index.

As described above, according to the present embodiment, by using the fatigue index value, it is possible to provide a fatigue management system S capable of managing fatigue for each part of a construction machine more accurately than before. .. The construction machine to be managed by the fatigue management system S of the present embodiment is not limited to the hydraulic excavator 10.

FIG. 10 is a side view of the dump truck 20 showing another example of the construction machine managed by the fatigue management system S. The dump truck 20 is a large transport vehicle that transports objects to be transported, such as pyroclastic materials mined in a mine. The dump truck 20 includes, for example, a vehicle body frame 21, left and right front wheels 22F, left and right rear wheels 22R, left and right front wheel side suspension devices 23F, left and right rear wheel side suspension devices 23R, a loading platform 24, and left and right. It has a hoist cylinder 25, a cab 26, a traveling drive device 27, and a building 28.

The vehicle body frame 21 has, for example, a frame shape that supports the front wheel 22F, the rear wheel 22R, the front wheel side suspension device 23F, the rear wheel side suspension device 23R, the loading platform 24, the hoist cylinder 25, the cab 26, the traveling drive device 27, and the building 28. It is a structure of.

The left and right front wheels 22F are steering wheels rotatably supported by the front portion of the vehicle body frame 21. The left and right rear wheels 22R are drive wheels rotatably supported by the rear portion of the vehicle body frame 21. The left and right front wheel side suspension devices 23F are attached to the front portion of the vehicle body frame 21 and elastically support the left and right front wheel 22F.

The left and right rear wheel side suspension devices 23R are provided at the rear portion of the vehicle body frame 21 and elastically support the left and right rear wheel 22R. The upper ends of the left and right rear wheel side suspension devices 23R are attached to the left and right brackets 21b provided at the rear of the vehicle body frame 21. The lower ends of the left and right rear wheel side suspension devices 23R are attached to the axle housing 27a of the traveling drive device 27.

The loading platform 24 is tiltably mounted on the vehicle body frame 21, and is, for example, a large container having a length of more than 10 meters in the front-rear direction of the dump truck 20, and carries a large amount of mined crushed stone or the like. In the loading platform 24, for example, the rear portion of the bottom portion is connected to the left and right brackets 21b of the vehicle body frame 21 via the connecting pin 21p, and the front portion of the bottom portion is connected to the upper end of the hoist cylinder 25.

The lower ends of the left and right hoist cylinders 25 are rotatably connected to the vehicle body frame 21, and the upper ends are rotatably connected to the loading platform 24. The hoist cylinder 8 is, for example, a hydraulic cylinder. As a result, when the hoist cylinder 25 is extended, the loading platform 24 rotates about the connecting pin 21p and tilts to a discharge position where the front portion is located upward and the rear portion is located downward. When the hoist cylinder 25 contracts from this state, the loading platform 24 rotates in the opposite direction around the connecting pin 21p and returns to the loading position shown in FIG.

The traveling drive device 27 is connected to the left and right rear wheels 22R and rotationally drives them. The traveling drive device 27 has, for example, an axle housing 27a and a bracket 27b. The axle housing 27a is provided, for example, in a cylindrical shape that accommodates a traveling motor, a speed reducing device, and the like (not shown) and extends to the left and right. The bracket 27b is provided, for example, so as to project forward from the axle housing 27a. The front end portion of the bracket 27b is rotatably attached to the mount member 21m of the vehicle body frame 21.

The building 28 defines a machine room at the front of the vehicle body frame 21. The building 28 houses an engine, a hydraulic pump, and the like (not shown) inside. The cab 26 is provided on a flat floor located at the top of the building 28. The cab 26 is provided in a box shape and defines a driver's cab on which the operator is boarded. Although not shown, the cab 26 is provided with a driver's seat, a steering wheel, an operation pedal, and the like on which the operator sits.

The dump truck 20 includes, for example, a controller similar to the controller 15 of the hydraulic excavator 10 shown in FIG. The controller of the dump truck 20 constitutes, for example, a stress calculation unit S1, a damage degree calculation unit S2, and an index value calculation unit S3. Further, the dump truck 20 is provided with an attitude sensor that detects the attitude of the dump truck 20. The posture sensor can be configured by, for example, an acceleration sensor.

Further, the cylinders of the front wheel side suspension device 23F and the rear wheel side suspension device 23R of the dump truck 20 are provided with a hydraulic sensor similar to the hydraulic sensor 18b of the hydraulic excavator 10. The hydraulic pressure sensor of the dump truck 20 is, for example, a force sensor that detects a force acting on the front wheel side suspension device 23F and the rear wheel side suspension device 23R. Further, the dump truck 20 is provided with a transmitter 19A and a monitor 19B, for example, like the above-mentioned hydraulic excavator 10 shown in FIG.

Therefore, according to the fatigue management system S of the present embodiment, like the hydraulic excavator 10 described above, the dump truck 20 can also manage the fatigue of each part of each component more accurately than before.

More specifically, as described above, the fatigue management system S includes a stress calculation unit S1, a damage degree calculation unit S2, and an index value calculation unit S3. With this configuration, the fatigue management system S, like the hydraulic excavator 10 described above, has, for example, conditions specific to each dump truck 20, each part of the dump truck 20, and each of a plurality of parts of the respective parts. Therefore, it becomes possible to manage the fatigue of each part of the dump truck 20 more accurately than before.

FIG. 11 is an image diagram showing an example of a monitor image of the fatigue management system S of the present embodiment. In the example shown in FIG. 11, the monitor 19B displays an image G in which each of the plurality of parts of the vehicle body frame 21 of the dump truck 20 is associated with the fatigue index value. Also in the fatigue management system S of the present embodiment, the fatigue index value of each part of each component of the dump truck 20 can be visually shown as in the example shown in FIGS. 7A to 7C.

Although the embodiment of the fatigue management system according to the present disclosure has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the design change is not deviated from the gist of the present disclosure. Etc., but they are included in this disclosure.

1 Hydraulic cylinder 10 Hydraulic excavator (construction machinery)
15b Storage unit 18 Sensor 18a Angle sensor (posture sensor)
18b Hydraulic sensor (force sensor, pressure sensor)
18c Angular velocity sensor (attitude sensor)
18d Accelerometer (posture sensor)
18e Tilt angle sensor (posture sensor)
19B monitor (image display device)
20 Dump truck (construction machinery)
140 Server 150 Storage device 160 Information terminal (comparison unit)
G Image S Fatigue management system S1 Stress calculation unit S2 Damage degree calculation unit S3 Index value calculation unit (image generation unit)

Claims (6)

A stress calculation unit that calculates the stress acting on multiple parts of the construction machine based on the output of the sensor attached to the construction machine.
A damage degree calculation unit that calculates the cumulative damage degree of each of the parts based on the stress, and a damage degree calculation unit.
An index value calculation unit that calculates a fatigue index value weighted to the cumulative damage degree for each of the parts.
Fatigue management system characterized by being equipped with. The fatigue management system according to claim 1, wherein the sensor includes a force sensor that detects a force acting on the construction machine and an attitude sensor that detects the posture of the construction machine. A storage unit in which a condition for selecting one fatigue index value or a numerical value for the weighting for each part from a plurality of different weighted fatigue index values or a numerical value for the weighting is stored. Equipped with
The fatigue management system according to claim 1, wherein the index value calculation unit selects one fatigue index value or a numerical value for weighting according to the conditions for each portion. As the condition, the storage unit stores the degree of agreement between the actual stress acting on each of the parts and the stress calculated by the stress calculation unit, and also stores the threshold value of the degree of agreement and the cumulative degree. A first map that increases the fatigue index value as the degree of damage increases, and a second map that increases the fatigue index value earlier than the first map as the cumulative degree of damage increases. , Is remembered,
The index value calculation unit selects the first map for each of the parts when the degree of coincidence is equal to or greater than the threshold value, and when the degree of coincidence is lower than the threshold value, the first map is selected. The fatigue management system according to claim 3, wherein the map of 2 is selected. The fatigue according to claim 1, further comprising an image generation unit that generates an image in which each of the parts of the construction machine is associated with the fatigue index value, and an image display device that displays the image. Management system. A server that performs data communication with the plurality of construction machines, a storage device connected to the server, and an information terminal that performs data communication with the server are provided.
The fatigue management system according to claim 1, wherein the information terminal has a comparison unit for comparing fatigue levels based on time-series data of the fatigue index value.

Images